Roh, 62, died from massive head injuries after leaping into a ravine while on a climbing trip near his home in Bongha village near the south-east coast, according to local media reports.

The former democracy activist, whose five-year term ended in February 2008, was said to have been under intense pressure amid allegations that he had accepted US$6m in bribes while in office.

Roh, who rose from an impoverished childhood to occupy the presidential Blue House, left a suicide note in which he hinted at ill health and talked of being unable to confront “countless agonies down the road”.

The note, the text of which was released by the Yonhap news agency, said: “The rest of my life would only be a burden for others. I can’t do anything because I’m not healthy. I can’t read books, nor can I write. Don’t be too sad. Isn’t life and death all part of nature? Don’t be sorry. Don’t blame anybody. It’s fate. Please cremate me. And please leave a small tombstone near home. I’ve long thought about that.”

Lee Myung-bak, the country’s present leader, said Roh’s death had left him “stricken with sorrow and deep sadness”. He broke away from talks with Vaclav Claus, the Czech president, to instruct authorities to organise a state funeral.

Roh’s predecessor, Kim Dae-jung, speculated that his “lifelong comrade in democracy” had been unable to bear the “intense pressure” caused by media reports about his family’s alleged involvement in the scandal.

Roh had faced police questioning over allegations that he had taken the bribes from a wealthy shoemaker via his wife and other relatives. He admitted that his wife had accepted US$1m but insisted it was to settle a debt, not a bribe. He said that he believed that US$5m given to another relative was intended as a legitimate business investment.

Despite his denials, late last month Roh publicly apologised for the disruption caused by the reports. “I feel ashamed before my fellow citizens,” he said, before being led away by prosecutors for questioning. “I am sorry for having disappointed you.”

Local reports said that Roh had left home early yesterday to climb a nearby peak with a bodyguard and fell 20 to 30 metres after jumping from a cliff known as Owl Rock. He was taken to Busan University Hospital but pronounced dead at around 9.30am local time.

Despite the corruption charges, reports said Roh had been leading a quiet life and was often seen around the village, smoking cigarettes and drinking with locals.

Roh, a self-trained lawyer who defended students accused of sedition during South Korea’s period of military rule, won a surprise victory in 2002 and took office the following year with promises to fight corruption and strengthen South Korea’s fledgling democracy.

Critical of the Bush administration’s foreign policy, Roh sought to improve ties with North Korea, and in 2007 signed a string of economic agreements with the secretive regime’s leader, Kim Jong-il, at a rare inter-Korean summit in Pyongyang.

However, initial support for his “sunshine policy” of engagement – begun by his predecessor – and unconditional aid weakened towards the end of his presidency.